linux/config.h missing - can't build modules

[Hans du Plooy <koffiejunkielistlurker@koffiejunkie.za.net>]

Hi guys,

I'm running the latest 2.6.21-rc kernels (to have my ACPI work - you
know, switch on the fans when the CPU get too hot).

I'm having trouble building modules, and I'm not too clued up on how the
kernel build system works.  I get this error:

theluggage:/usr/src/modules/spca5xx# make
   Building SPCA5XX driver for 2.5/2.6 kernel.
   Remember: you must have read/write access to your kernel source tree.
make -C /lib/modules/`uname -r`/build SUBDIRS=/usr/src/modules/spca5xx
CC=cc modules
make[1]: Entering directory `/usr/src/linux-2.6.21-rc6'
  CC [M]  /usr/src/modules/spca5xx/drivers/usb/spca5xx.o
/usr/src/modules/spca5xx/drivers/usb/spca5xx.c:39:26: error:
linux/config.h: No such file or directory

Now I checked, in the kernel source of 2.6.18 as shipped with Etch/Sid,
config.h is in /usr/src/linux-source-2.6.18/include/linux/config.h
but in 2.6.21 there is no config.h in include/linux/

How do I get around this?

Thanks
Hans